Device for cooling workpieces which are submitted to a vacuum treatment

ABSTRACT

A cylindrical jacket of rubber-like elastic material is mounted on a rotary drum forming part of the equipment of a chamber for vacuum coating, and it is hermetically sealed with each end of the drum so that the drum interior is separated from a surrounding evacuated space of a treatment chamber. The workpieces to be coated are supported on the periphery of the cooling jacket which is stretched against the bottom surfaces of the workpieces so as to create a heat conduction contact. The jacket is cooled by coolant which is circulated from outside the vacuum chamber through the drum shaft and around the inner jacket surfaces and out through an annular conduit surrounding the drum shaft. The coolant flow causes a pressure difference between the drum interior and the chamber surrounding the drum so that the inflating cooling jacket applies tightly against and, because of the suppleness of the material, conforms exactly to the shape of the workpiece surfaces. The workpieces may be supported exteriorly by a cylindrical cage or grid which encompasses the cooling jacket and, at the same time, forms a limiting means for the inflation of the jacket.

United States Patent 1191 Wagner DEVICE FOR COOLING WORKPIECES WHICH ARE SUBMITTED TO A VACUUM TREATMENT [75] lnventor: Rudolf Wagner, Buchs, Saint Gall,

Switzerland [73] Assignee: Balzers Patent-Und Beteiligungs-Aktiengesellschaft, Balzers, Furstentum, Liechtenstein [22] Filed: Oct. 24, 1972 [21] Appl. No.: 300,373

[30] Foreign Application Priority Data [4 June 25, 1974 Primary E.raminerManuel A. Antonakas Assistant E.taminer-Daniel J. OConnor Attorney, Agent, or Firm-McGlew and Tuttle [57] ABSTRACT A cylindrical jacket of rubber-like elastic material is mounted on a rotary drum forming part of the equipment of a chamber for vacuum coating, and it is hermetically sealed with each end of the drum so that the drum interior is separated from a surrounding evacuated space of a treatment chamber. The workpieces to be coated are supported on the periphery of the cooling jacket which is stretched against the bottom sur- Oct. 27, 1971 Switzerland 015692/71 faces of the workpieces so as to create a heat conduction contact. The jacket is cooled by coolant which is [52] U.S. Cl 165/86, 118/491, 118/69, circulated from outside the vacuum chamber through 118/301, 118/503, 165/89, 204/298 the drum shaft and around the inner jacket surfaces [51] Int. Cl. F28d 11/02 and out through an annular conduit surrounding the [58] Field of Search 165/89, 46; 1 18/301, 505, drum shaft. The coolant flow causes a pressure differ- 1 18/49 ence between the drum interior and the chamber surrounding the drum so that the inflating cooling jacket [56] References Cited applies tightly against and, because of the suppleness UNITED STATES PATENTS of the material, conforms exactly to the shape of the 1 185 131 5/1965 Manning 118/505 workpiece Surfaces- The workpieces may be Supported 313441772 10/1967 Lobash @1511..." M13. 118/301 exteriorly by a Cylindrical cage of g Which encom- 3,555,309 ll/l967 Bender et al. 118/505 Passes the coohhgjacket and, at t same time, ms 3,383,238 5/1968 Unzicker et al, 118/49 a limiting means for the inflation of the jacket. 3,498,260 3/1970 De Jean et al 118/301 3,638,606 2/1972 Pieper CI al 118/301 5 Claims, 2 Drawing Figures A j! j 9 a g 2 [Z A 7 i W\ 0 k a a f l a a '7 i u "W if, j 5/ if g W DEVICE FOR COOLING WORKPIECES WIHCH ARE SUBMITTED TO A VACUUM TREATMENT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates, in general, to vacuum treating devices and in particular to a new and useful device for cooling articles which are treated under vacuum conditions and which includes a jacket of rubber-like elastic material which forms the cylindrical skin of a rotary drum located in a vacuum chamber which is cooled from within by a separate coolant circuit and is adapted to apply tightly against workpieces arranged on the drum circumference so as to efficiently abduct the heat therefrom.

2. Description of the Prior Art In numerous vacuum treatments, particularly in the coating of workpieces by thermal evaporation or by cathode sputtering, heat is transferred to the treated workpiece by radiation, or as-kinetic energy of particles incident on the surface thereof or is liberated by condensation. In order to avoid an inadmissible increase of the temperature, appropriate cooling is necessary. In such treatments, however, the heat energy can be carried off the workpiece surface again by radiation or by contact with a cooling body. This is because in a vacuum there is no possibility that the heat can be ab-v sorbed by an ambient atmosphere such as is frequently employed in other cooling techniques. But, in many cases, the removal of heat by radiation is unsufficient especially if the maximum admissible temperature of the workpiece to be treated is relatively low, for example, must not exceed 200 C. Thus, heat removal must be effected through bodies which are in contact with the workpiece. However, the establishment of a good thermal contact between a workpiece and a cooling body proves to be difficult because either the contact is only possible at individual points of the adjacent surfaces or a preliminary fine machining of the surfaces would be necessary to insure a satisfying heat conducting surface contact.

In other fields, outside the vacuum technique, the problem of establishing a thermal contact for heat abduction is also present, but there it is not so serious as under vacuum conditions because in the presence of a gas atmosphere of enough high pressure (atmospheric pressure) the gas, filling up the small cavities between the two surfaces of the workpiece and the cooling body which are pressed together, substantially contributes, by convection, to the heat dissipation. As mentioned above, in a vacuum. this is not possible.

Up to now, workpieces to be cooled are simply fixed to holding devices which, being cooled at their turn, function as cooling bodies. These cooling bodies may be hollow and flown through by a coolant, for example, by cooling water or pressure air.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a device for cooling workpieces which are submitted to a treatment in vacuum conditions, comprising a cooling jacket which is, preferably, mounted on a rotary drum forming part of the equipment of a vacuum chamber so as to hermetically separate the interior of the jacket from the evacuated space and which is cooled from within by a coolant circulating in an independent circuit operated from the outside.

As a particular improvement provided by the invention, the cooling jacket is made of a rubber-like elastic material. The jacket is mounted on the rotary drum so that it forms the outer skin thereof coming into direct contact with the bottom surfaces of the workpieces which are fixed to the periphery of the drum either directly or indirectly by means of a supporting cage or holding grid shaped according to the shape and dimensions of the individual workpieces.

The cooling of the jacket makes use of the known practice of cooling hollow bodies by a continuous stream of a cooling agent and, in a preferred embodiment of the invention, the coolant is introduced through the hollow shaft of the rotary drum, flows around the interior walls of the jacket and passes, throughan annular passage formed around the drum shaft, to an outlet provided outside the vacuum chamber.

The pressure difference established by the cooling system between the interior of the jacket and the evacuated space of the vacuum chamber causes the jacket automatically and tightly to apply against the workpiece retained on the circumference of the rotary drum and, owing to the elasticity of the material, exactly to conform to almost any shape of the bottom surface of a workpiece. The perfect surface contact thereby obtained results in an efficient and reliable cooling of the pieces during the whole treatment.

Workpieces of relatively large dimensions may be fixed, for example, to the head plates of the rotary drum. For workpieces of relatively small dimensions, however, it is advantageous to place or fix the same in a supporting, preferably cylindrical, cage or grid embracing the rotary drum and, in this case, the cooling jacket applies against the free bottom surfaces of the workpieces protruding from the openings in the cage or grid. At the same time, the cage or grid acts as a structure limiting the maximum possible inflation of the jacket in radial direction.

Accordingly, it is an object of the invention to provide a device for an effective and reliable cooling of workpieces which are submitted to a vacuum treatment, particularly to a vacuum coating, and which are supported on the outside of a rotary drum forming part of the equipment of a vacuum chamber, comprising a cooling jacket which is mounted on the drum, adapted to apply against the workpieces supported thereon and which is made of a rubber-like elastic material.

A further object of the invention is to provide a hermetic mounting of the cooling jacket on the drum so that the interior of the jacket as well as the inlet and outlet coolant conduits are separated from the evacuated space in the vacuum chamber and a pressure difference can be created.

Another object of the invention is to provide an independent coolant circuit in which the coolant continuously flows around the inner surfaces of the jacket thereby cooling the jacket walls and, simultaneously, creating a pressure causing the same to apply against the workpieces.

According to a feature of the preferred embodiment of the invention, the workpieces are supported on the drum by a preferably cylindrical cage or grid which, at the same time, forms a limiting means for the inflation of the cooling jacket.

According to another feature 'of the inventiomthe wall or wall portions of the cooling jacket'may already in manufacture be conformed to the surfaces of the workpieces to be contacted.

For an understanding of the principles of the invention, reference is made to the followingdescription of typical embodiments thereof as illustrated in theac companying drawing. I g V r r BRIEF DESCRIPTION OF THE DRAWING In the'Drawing: J I

F IG; 1 is a schematicelevationalview, partly in section, of an apparatus for vacuum coating by evaporation constructed in accordance with the invention; and

FIG. 2is a partial sectional view of the elastic jacket shown in FIG. 1 with optical lense workpieces to be 7 coated. I

GENERAL DESCRIPTION, OF THE PREFERRED,

EMBODIMENTS;

Referring to the drawing in particular,the inventive jacket 10 forming the cylindricalouter skin of the, V drurn'S, is madeof a material of rubbenlike elasticity.-

' In the present example, the workpieceto becoated by evaporation, could be a metal sheet. 11 of cylindrical V 7 shape which is arranged on the peripheral surface of j the rotary drum 5 so as to be supported by the head plates13 and 16. Owing to the pressure difference crerated by the cooling system between the interior and the exterior of the cooling jacket 10, the rubber-like elastic wall ofjacket 10 is tightly applied against. the inner surface of the sheet to be coated and, consequently, cools the same very efficiently. Another advantage, due to the elasticity of the jacket, is that when the vacuum:

' chamber is opened, the jacket 10 may very rapidly and easily be removed from: the drum, or slipped over again.

Furthermore, the jacket since it is tightly applied f' 7 against the workpiece, insures an absolute conformity device embodied therein comprisesan apparatus for vacuumcoating'comprising a tank or vessel 1 defining a vacuum chamber which can be evacuated by means of a pump 2 through a pipe 3 so as to produce the very low pressure necessary for the'intended coating process. In the present example, a coating by evaporation is provided, and to this purpose, thechamber l is equipped with a structure 4 which for example comprises a'support serving to support substances tobe evaporated or a cathode ofa cathode sputtering device. I

of rotary motion between the drum and the-workpiece and a continuous regular rotation of the drumris provided, a more regular deposition of the evaporated substance or otheradvantages may be obtained.

The workpiece may be a simple cylindricalsheet as:

shown in FIG. 1 or workpieces of other shape such as a lenseas shown in FIG. 2. The metal sheet 11 shown in FIG. 1 may not be a workpiece but a support for' I other' workpieces if desired. Such a support, for instance, could be provided with recesses or hollowed spaces in which optical'lenses to be coated by evaporation could be placed. In such a case, the rubber-like elastic jacket 10 istightly applied both against the lenses 12 and the intermediate surfaces of the support A rotary drum 5 adapted to hold the workpieces to be 1 coated is disposed, in front of the structure 4. The drum 5 is unilaterally supported by and rotatably mounted in a bearing 6 which is fixed to the wall of the vessel 1.

The drum 5 comprises two end parts or heads 5a and 5b,-e'ach assembled of two circular plates l3, l4 and I5, 16 respectively, which are held together, for example, by bolts 20. A central shaft 8 supports the heads 5a and SI) for rotary motion therewith.

In accordance with the invention, a cylindricalela stic 7 support or cooling jacket 10 has its respective ends en'- gaged between and clamped by the two circular plates 13, I4 and. l5, 16 forming the drum heads 5a and 5b. The shaft portion 8 or, as in the represented embodias shown in FIG. 2.v Evidently, many other shapes of V supporting devices for workpieces may be employed.

In the last embodiment shown in FIG; 2, the support for the workpieces comprises a cage, or grid II embracing. the drum and Iimitingthe maximum possible expansion or inflation of the cooling jacket in a radial direction. For workpieces with a particular uniform surface, it isadvantageous to manufacture the rubberlike elastic jacket 10 in a conformable particular.

shape. The jacket 10 could, for example, have concave depressions corresponding to the convex lens surfaces.

ment, the coaxial motor shaft'portion 9 of smaller diameter is mounted in the bearing 6, and driven by a motor 7. The bearing 6 is fixed to the wall 1 ofthe vacuum chamber and includes a hermetic sealing for the shaft 9 passing therethrough. Inlet and outlet conduits 21 and 22 are provided for circulating a cooling medium to the interior ofjacket 10. To this purpose, the

respective portions of the motor shaft 9 and of shaft 8 are hollow to define axial flow conduit '23 and cross bores 24 areprovided at the ends of the. hollow por-, tions to provide for flow into the hollow drum 5. Moreover, annular passages 25 and 26 in the circular plates 15, I6 and bores 27, 28 in a supporting disk 29 connecting the shaft 8 with the plate 16 as well as a tubular conduit 17 flanged to this platetl6 are provided as pasi In general, however, the cooling jacket is sufficiently flexible to conform to. the surface of any workpiece in a satisfactory manner.

The application of the invention is in no way limited.

to the processof vacuum coating by evaporation. For

example, the structure 4 may comprise a cathode of a cathode sputtering device, or it could simply be a heata ing device for a heat treatment of a workpiece surface requiring a simultaneous cooling as protection against sages for the return flow of thecoolant. In FIG. I, the

circulation of the coolant, which has to cool the interior surfaces of jacket 10 coming into contact with the treated workpieces, is indicated by arrows 30.

In order to assure a perfect conformation of the cool ing wall to the surface of the cooled workpiece,rthe

. superheat, or any otherdevice for a process in which wise without departing from such principles.

What is claimed is: I l. A device for cooling a workpiece which is submitted to a treatment, particularly to'a vacuum coating,

and which is supported on the outside of a casing structure with their exterior surfacesexposed for treatment,

comprising a drum having an expandible cooling jacket forming a workpiece engagementsurface, the interior of said drum being hermetically sealed, means for directing a coolant into the-interior of said drum for cooling the interior of said jacket and for expanding said jacket against the workpiece, and an outer grid supporting structure engaged over said jacket for engaging the workpiece from the exterior thereof and holding it on said drum and limiting the maximum possible expansion of said jacket.

2. A device according to claim 1, wherein said cooling jacket comprises a hollow cylinder having an inner surface exposed to said coolant and having at least a portion comprising a rubber-like elastic material.

3. A vacuum treatment apparatus for use in a vessel having an evacuated chamber, comprising a rotary drum adapted to be positioned within the evacuated chamber having an end wall at each end and a cylindrical elastic jacket with a portion at each end engaged with and sealed to respective ones of said end walls, said drum having a shaft with means for rotatably mounting said shaft on the vessel wall and for circulating a coolant into the interior of said drum for cooling of the interior of said jacket and subsequently withdrawing the coolant from said drum, and holding means for holding a workpiece over the exterior surface of said jacket, said jacket being expandible by the circulation of said coolant into heat absorbing contact with the workpiece, said holding means comprising a cage disposed around said jacket having portions engageable with the periphery of a workpiece and exposing the exterior surface of the workpiece for treatment and limiting the expansion of said jacket.

4. A vacuum treatment apparatus according to claim 3, wherein said drum end walls include inner and outer plates clamped together over the respective ends of said jackets.

5. A vacuum treatment aparatus according to claim 3, including a vessel defining the evacuation chamber and a treatment structure located with said vessel alongside said jacket in a position to expose the exterior of the workpiece to treatment from said structure. 

1. A device for cooling a workpiece which is submitted to a treatment, particularly to a vacuum coating, and which is supported on the outside of a casing structure with their exterior surfaces exposed for treatment, comprising a drum having an expandible cooling jacket forming a workpiece engagement surface, the interior of said drum being hermetically sealed, means for directing a coolant into the interior of said drum for cooling the interior of said jacket and for expanding said jacket against the workpiece, and an outer grid supporting structure engaged over said jacket for engaging the workpiece from the exterior thereof and holding it on said drum and limiting the maximum possible expansion of said jacket.
 2. A device according to claim 1, wherein said cooling jacket comprises a hollow cylinder having an inner surface exposed to said coolant and having at least a portion comprising a rubber-like elastic material.
 3. A vacuum treatment apparatus for use in a vessel having an evacuated chamber, comprising a rotary drum adapted to be positioned within the evacuated chamber having an end wall at each end and a cylindrical elastic jacket with a portion at each end engaged witH and sealed to respective ones of said end walls, said drum having a shaft with means for rotatably mounting said shaft on the vessel wall and for circulating a coolant into the interior of said drum for cooling of the interior of said jacket and subsequently withdrawing the coolant from said drum, and holding means for holding a workpiece over the exterior surface of said jacket, said jacket being expandible by the circulation of said coolant into heat absorbing contact with the workpiece, said holding means comprising a cage disposed around said jacket having portions engageable with the periphery of a workpiece and exposing the exterior surface of the workpiece for treatment and limiting the expansion of said jacket.
 4. A vacuum treatment apparatus according to claim 3, wherein said drum end walls include inner and outer plates clamped together over the respective ends of said jackets.
 5. A vacuum treatment aparatus according to claim 3, including a vessel defining the evacuation chamber and a treatment structure located with said vessel alongside said jacket in a position to expose the exterior of the workpiece to treatment from said structure. 